Various manifolding systems for handing various fluids, both gases and liquids, have been known for many years. In particular, the mounting of a number of fluid handling valves on unitary blocks of steel or other suitable materials have been known for years. In such systems the valves are generally mounted so as to intercede in various flow paths extending through the blocks so as to be useful in alternately opening and closing those paths. Additionally, the modularization of these systems and interconnection between various modules has also been known.
In particular, one such type of system is shown in Tinsley et al, U.S. Pat. No. 3,234,964, which shows a manifold for distributing a gas under pressure. One of the blocks in the manifold system shown in Tinsley et al includes seven valve seats to receive seven standard valves for gas distribution through various outlet ports therein. Several of these valves are used in Tinsley et al for the measurement of gas pressure in various gas lines and for the measurement of gas flow rates therethrough.
U.S. Pat. No. 2,247,140 to Twyman discloses another multiple valve unit which has a housing which is compactly and directly connected to simialr valve units. In fact, the patentee himself states in this patent that the joining of the valve housings will eliminate considerable piping and form a directional control unit which is compact and convenient to operate. Similarly, Gray, U.S. Pat. No. 2,834,368, provides a valve fitting which in a single form can receive any of the various types of valves functionally necessary in hydraulic circuits. This is said to enable selected numbers of fittings to be arranged in juxtaposition into a unitary assembly so as to embody all of the selected valve functions of the system without requiring piping connections between the various valves.
Valve manifolds which are capable of receiving standard commercially available valves have also been disclosed, such as in Loveless, U.S. Pat. No. 3,244,193. Furthermore, the overall concept of modular valve blocks being used in such systems are shown in the following U.S. patents: Sartakoff, U.S. Pat. No. 1,797,591; Gray, U.S. Pat. No. 2,834,368; Beckett et al, U.S. Pat. No. 3,111,139; Barton, U.S. Pat. No. 3,158,164; Lyon, U.S. Pat. No. 3,234,963; Raymond, U.S. Pat. No. 3,589,387; Kiernan, U.S. Pat. No. 3,654,960; Jeans et al, U.S. Pat. No. 3,680,589; Murata, U.S. Pat. No. 3,766,943; and Stoneman et al, U.S. Pat. No. 3,806,088.
The search has continued, however, for such modular systems which can be applied to the specific application not only of handling gases but of handling gases under high vacuum conditions, furthermore, one which has a high degree of flexibility, and can be removably interconnected with additional modular units without the need for excessive welding of conduits between them. Furthermore, such systems have been sought which are capable of handling expensive gases so that the amount of gas lost to dead space in interconnecting pipes is kept to a minimum. Such systems are particularly useful in connection with processes for the growth of crystals such as in the production of semiconductors, and in which such epitaxial systems employ various generally expensive gases which must be carefully controlled and monitored.